Mr.Arindam Banerjee has developed a conceptual framework for the creation of
a hydrogen economy in the Australian context. His report analyses the potential
benefits of a hydrogen economy(economic and environmental). It highlights the
fact that Australia could not only meet its increasing energy demands but at the
same time become a world leader in taking initiative to move towards green
technologies for energy generation and consumption. Since hydrogen storage is a
challenge the above mentioned idea directly looks at use of piping network for
transportation of hydrogen. Based on this novel framework developed by Mr.
Banerjee the following report looks at the technical challenges associated with
making the hydrogen economy a reality.

The Hydrogen economy is one of the probable green technology based solutions
which could replace the oil driven economies looking at future environmental
concerns. Scientifically an optimized hydrogen economy would operate with zero
carbon emissions and produce soft water as a by product making it an lucrative
solution. This fact is further validated by the amount of funding allocated for
the development of a hydrogen economy globally. A lot of technical and economic
challenges exist before the concept of a hydrogen economy can be put to
commercial use. The following review outlines various project stages involved in
making the hydrogen economy a reality in the Australian context.

Challenges in a hydrogen economy:

The major challenges involved in developing an hydrogen economy are as
follows

1) Selection of proper technologies for production of hydrogen

2) Design of a piping network for transportation of hydrogen in gaseous or in
liquid form Design of valves and compressors for transportation of hydrogen.

3) Design of valves , compressors and sensors for transportation of hydrogen.

5) Cost optimization studies to make the project as cheap as possible.

Selection of proper technologies for production of hydrogen:

There are three basic procedures for generation of hydrogen they are
Electrolysis by use of direct current, generation of hydrogen via a fuel cell
and finally generation of hydrogen from fossil fuel sources. Among these
technologies direct route electrolysis is energy intensive compared to others
but at the same time is pollution free. The generation of hydrogen by fuel cell
technology (microbial sources can be used) is cost effective but the power
generation rate is comparatively lower as compared to direct electrolysis.
Finally the last method is to use fossil fuel sources which is relatively
expensive as compared to fuel cell technologies and has higher carbon emissions
as well but it provides a relatively stable throughput. The procedure for
generation of hydrogen would be actually a optimized mix of all the three
mentioned technologies with cost, geographic location, and carbon emission as
boundary conditions for a optimization problem. Also further research and
development in this area could lead to improvement in efficiency and throughput
rates for fuel cell technologies resulting in economies of scale with respect to
fuel cell technologies.

Design of a piping network for transportation of hydrogen in gaseous or in
liquid form

The piping of natural gas using steel pipes is a well known technology. A lot
of research has been put in to understanding the economics of piping of hydrogen
using existing technology. The literature suggests that the piping of hydrogen
is going to at least 50% more expensive as compared to natural gas due to the
following reason.

Firstly Hydrogen is more corrosive as compared to natural gas. The problem of
hydrogen embitterment due to hydrogen corrosion and documented .So the cost of
hydrogen resistant pipes is going to costlier using conventional technologies
for transportation like say steel pipes. Secondly special fittings and valves
have to be designed using the conventional piping mechanism to eliminate
hydrogen permeation which would further increase the cost. Finally handling of
specially designed pipes and valves would result in increased labour costs which
would further add on. It has been proved in the literature that the major cost
in laying a piping network is the labour cost and hence is an important factor.

There are other possible research alternatives to eliminate this problem and
make the piping of hydrogen more sustainable and cheaper probably comparable or
even cheaper as compared to pumping natural gas or other fuel gases. The
possible research in this area will be discussed later in the report. Also the
cost of pumping hydrogen like other forms of energy is dependent on the
geographic location and the demand which result in economies of scale.

Design of valves, compressors and sensors for transportation of
hydrogen

The design of valves, compressors, connecting ports and sensors are very
important for the use of a piping network in an hydrogen economy. The reason
being that the use of special materials for hydrogen transportation would
require special accessories as well. Further the sensitivity of the valve also
needs to be optimized as per the energy load. The current gas compressions
systems need to be modifies considering the corrosive nature of hydrogen as
compared to natural gas or steam. Also the liquefaction of hydrogen will take
place at much higher pressures and lower temperatures changing the overall
efficiency of the compression cycle. Hence design studies of the accessories to
be used are very important for the success of a hydrogen economy.

Thermodynamic efficiency of hydrogen energy cycle for generation of
electricity

It has been known since ages that the Carnot cycle is the best thermodynamic
cycle for generation of energy and hence is the bench mark for any kind of
thermodynamic studies. The reason being that a Carnot cycle is a completely
reversible cycle and operates infinitesimally slowly maintaining reversibility
of the process at every stage. All other commercially used energy cycles cannot
be operated so slowly and are not completely reversible. Hence the efficiency of
any other commercially used energy generation cycle will always be lesser than
an idealized Carnot cycle. The conversion efficiency of a fuel cell under
idealized conditions can be higher or equal to Carnot cycle but the overall
efficiency of energy conversion i.e. hydrogen - electricity - hydrogen can never
be greater than a idealized Carnot cycle. Though there is sufficient literature
in this area the claims need to be verified experimentally. Also further studies
on the conversion efficiency of hydrogen - electricity - hydrogen need to be
calculated experimentally and suitable thermodynamic models need to be developed
before actually commercializing.

Cost optimization studies on hydrogen generation and supply

The generation and supply of hydrogen has to be cost effective in the sense
approximately at least equal to the case of a gas electricity generation system
to make it economically competitive. Also the additional benefits of using
hydrogen as compared to conventional technologies will make the proposition even
more effective. The key to cost optimization is to develop and select suitable
technologies for generation and transportation of hydrogen. The possible
research projects to reduce the generation and transportation cost of hydrogen
will be discussed further in this report.

Project planning and scheduling:

The diagram below illustrates the various stages involved and the time lines
required for development of a workable model for use of hydrogen energy. The
overall project would require around 6.5 - 7 years before it can be commercially
converted in to a real time system. Also with sufficient amount of manpower and
funding the time scale of lab scale studies can be reduced suitably.

Role of Rheology and Material processing Centre (RMPC): (Example
proposal)

The transmission of hydrogen using conventional steel pipes is not a viable
solution since hydrogen is highly corrosive (hydrogen embrittlement). Also the
rate of permeation of hydrogen from the conventional pipes is very high. The
cost of laying specially designed steel pipes is very high making hydrogen
transmission uneconomical as compared to natural gas. Development of reinforced
polymeric composites with reduced permeability is a good alternative to be used
.The use of such composites will not only eliminate the problem of hydrogen
corrosion and embrittlement at the same time make it cost effective and
comparable to that of natural gas transmission. Such a kind of project has been
taken up by the Argonne research lab in USA.Once a suitable material is selected
then a piping network design can be made and sensors can be incorporated in to
the system to monitor flow rates and pressure of hydrogen inside the pipes .Once
the piping network has been designed then hydrodynamic and thermodynamic
modelling of hydrogen flow through the pipes becomes very essential since this
will help in determining the suitable points for installing compression ports .
Also further work would be to incorporate valves and joining ports with in the
piping system. Then this network can be used commercially.